pixman-filter: Made Gaussian a bit wider

Expanded the size slightly (from ~4.25 to 5) to make the cutoff less
noticable.  Previouly the value at the cutoff was
gaussian_filter(sqrt(2)*3/2) = 0.00626 which is larger than the
difference between 8-bit pixels (1/255 = 0.003921). New cutoff is
gaussian_filter(2.5) = 0.001089 which is smaller.

v11: added some math to commit message
v14: left SIGMA in there
Signed-off-by: Bill Spitzak <spitzak@gmail.com>
Acked-by: Oded Gabbay <oded.gabbay@gmail.com>
Reviewed-by: Søren Sandmann <soren.sandmann@gmail.com>

diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
index 33188930713fdfe203a95771c5cc04aba188e02e..5f3b752f9b5c3cc00a20e1e5e170cb8f703d05ef 100644 (file)
--- a/pixman/pixman-filter.c
+++ b/pixman/pixman-filter.c
@@ -143,7 +143,7 @@ static const filter_info_t filters[] =
     { PIXMAN_KERNEL_BOX,               box_kernel,       1.0 },
     { PIXMAN_KERNEL_LINEAR,            linear_kernel,    2.0 },
     { PIXMAN_KERNEL_CUBIC,             cubic_kernel,     4.0 },
-    { PIXMAN_KERNEL_GAUSSIAN,          gaussian_kernel,  6 * SIGMA },
+    { PIXMAN_KERNEL_GAUSSIAN,          gaussian_kernel,  5.0 },
     { PIXMAN_KERNEL_LANCZOS2,          lanczos2_kernel,  4.0 },
     { PIXMAN_KERNEL_LANCZOS3,          lanczos3_kernel,  6.0 },
     { PIXMAN_KERNEL_LANCZOS3_STRETCHED, nice_kernel,      8.0 },